THE PRESENT INVENTION relates to an air-bag, and more particularly relates to an air-bag in the form of a so-called inflatable curtain.
It has been proposed to provide an air-bag in the form of a so-called “inflatable curtain” which is initially mounted in the roof of a vehicle and which, when inflated, extends adjacent the side windows of a motor vehicle.
Such inflatable curtains have to be inflated within a very short period of time, and consequently the inflator or gas generator that is associated with such an inflatable curtain is adapted to generate a substantial volume of gas in a very short period of time. The gas entering the air-bag, on deployment thereof, thus has very aggressive flow.
In order to minimise the risk of damage occurring to the fabric of the air-bag, it has been proposed to provide an air-bag of this type with an inner filling sleeve. An air-bag of this type is disclosed in GB-2357467A.
The inner sleeve is coaxial with the main gas flow duct, and it is, of course, important that gas is introduced to the air-bag through the inner sleeve. If, for example, a gas generator is connected to the inflatable curtain in such a way that gas is injected into the space between the inner sleeve and the ordinary gas flow duct, the ordinary gas flow duct will almost certainly be damaged by the aggressive flow of gas from the gas generator or inflator.
The present invention seeks to provide an improved air-bag in which the risk of mis-connecting the gas generator to the air-bag is minimised or obviated.
According to this invention there is provided an air-bag, the air-bag having a primary gas flow duct to lead from a gas generator to one or more zones within the air-bag to be inflated, and a separate inner gas flow duct mounted within the outer gas flow duct, the inner gas flow duct, and the outer gas flow duct, in the region to be connected to a gas generator, having areas thereof secured together.
In one embodiment two areas of the inner gas flow duct are secured to two respective areas of the outer gas flow duct.
Conveniently the outer gas flow duct is formed from two superimposed layers of fabric, and the inner gas flow duct is formed from two superimposed layers of fabric, the upper layer of fabric forming the outer gas flow duct being secured to an area of the upper layer of fabric forming the inner gas flow duct, and the lower layer of fabric of the outer gas flow duct being secured to an area of the lower layer of fabric of the inner gas flow duct.
Advantageously the said two areas are off-set and not superimposed.
In another embodiment the inner gas flow duct is provided with projecting ears which extend beyond the end of the outer gas flow duct, and which are folded back about a fold-line to lie adjacent the end of the outer gas flow duct, the ears being secured to the fabric forming the outer gas flow duct.
In one version of this embodiment each ear has a dimension which is no greater than the diameter, when flat, of the inner gas flow duct, each ear being folded back to lie adjacent a respective layer of fabric forming the outer gas flow duct, each ear being secured to the layer of fabric that it lies adjacent.
In a further version of this embodiment each ear has a dimension greater than the diameter of the inner gas flow duct when flat, the ears being folded back to lie adjacent the exterior of the outer gas flow duct, with parts of the ears not lying over the inner gas flow duct, the parts of the ears not lying over the inner gas flow duct being secured together, and being secured to the fabric forming the outer gas flow duct.
Preferably at least one said fold-line of a projecting ear is provided with a slot and the air-bag is provided with a tab located to pass through the slot. The tab on the air-bag may pass through the slot and prevent the inner gas flow duct from being over-inserted into the air-bag.
Preferably at least one ear is provided with an aperture, and the outer gas flow duct and the inner gas flow duct are also provided with apertures so that the apertures in the or each ear is aligned with co-operating apertures in the outer gas flow duct and the inner gas flow duct. Conveniently each ear is provided with an aperture, and the outer and inner gas flow ducts are each provided with two apertures.
Conveniently the inner gas flow duct is provided with at least one further aperture at a point spaced from the projecting ears.
Advantageously the said areas are on axially extending tabs which project axially beyond the ends of the inner and outer gas flow ducts.
In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which: